The present invention relates to a GNSS antenna with reduced multipath reception capable of cutting-off signals reflected from the ground. These signals are an important source of errors, so the decrease in reflected signals can lead to a higher positioning accuracy. This is especially critical for differential correction base stations. Signals from the satellites near the horizon are most vulnerable to distortions. To efficiently reject near-horizon satellite signals reflected from the ground, a special shape of directional patterns (DP) is required.
Different variants of such antennas are known, including vertical phase arrays, see, for example, U.S. Pat. No. 7,583,236, U.S. Pat. No. 5,534,882. Suppression of reflected signals is achieved by using a great number of radiators. This leads to a complex structure and a large vertical dimensions of the antenna. Moreover, there is an increase in losses in the antenna feeder, and a reduction of the antenna radiation efficiency.
There is also known an antenna structure where the radiator is on a flat (PCT/RU2013/000312) or spherical (U.S. Pat. No. 8,441,409) impedance ground plane. In this case, antenna radiation efficiency does not decrease, but a very large ground plane is needed to effectively reject signals from low satellites that are reflected from the ground.
The subject of this invention is an antenna system capable of decreasing the level of reflected signals, including that of low-elevation satellites, and yet guaranteeing smaller dimensions and structural simplicity.